# 创建一个待验证用户列表
# 和一个用于存储已验证用户的空列表。
unconfirmed_users = ["alice", "brian", "candace"]
confirmed_users = []

# 验证每个用户，直到没有未验证用户为止。
# 将每个经过验证的列表都移到已验证用户列表中。
while unconfirmed_users:
    current_user = unconfirmed_users.pop()
    print(f"Verifying user: {current_user.title()}")
    confirmed_users.append(current_user)

# 显示所有的已验证用户
print("\nThe following users have been confirmed:")
for confirmed_user in confirmed_users:
    print(confirmed_user.title())